Multipling 1216609 by its sum of digits (25), we get a square (30415225 = 55152).
Multipling 1216609 by its reverse (9066121), we get a square (11029924403689 = 33211332).
The square root of 1216609 is 1103.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9066121 = 30112.
It is a Duffinian number.
21216609 is an apocalyptic number.
1216609 is the 1103-rd square number.
1216609 is the 552-nd centered octagonal number.
It is an amenable number.
1216609 is an frugal number, since it uses more digits than its factorization.
1216609 is an odious number, because the sum of its binary digits is odd.
The cubic root of 1216609 is about 106.7538815782.
The spelling of 1216609 in words is "one million, two hundred sixteen thousand, six hundred nine".